/*
 * Licensed to ObjectStyle LLC under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ObjectStyle LLC licenses
 * this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package io.bootique.di;

import java.util.Objects;
import java.util.function.Supplier;

/**
 * Injection stack trace element.
 */
public class InjectionTraceElement {

    private static final Supplier<String> EMPTY_MESSAGE_SUPPLIER = () -> "";

    /**
     * Binding key of this trace element
     */
    private final Key<?> bindingKey;

    /**
     * Last human readable message for binding key.
     */
    private Supplier<String> message = EMPTY_MESSAGE_SUPPLIER;

    public InjectionTraceElement(Key<?> bindingKey) {
        this.bindingKey = bindingKey;
    }

    public void setMessage(Supplier<String> messageSupplier) {
        this.message = Objects.requireNonNull(messageSupplier);
    }

    public String getMessage() {
        return message.get();
    }

    public Key<?> getBindingKey() {
        return bindingKey;
    }

    public String toString() {
        if (message == null) {
            return bindingKey.toString();
        }

        return bindingKey + " -> " + message.get();
    }
}
